BLOOD ELABORATING GLANDS. 



361 



FIG. 156. 



organ. For this purpose one can either examine samples of the 

 blood from the artery and vein of the organ, while the ordinary 

 circulation is going on, or immediately after the removal of the 

 organ, by causing an artificial 

 stream of blood to flow through 

 it ; then the changes brought 

 about in the blood by its passage 

 through the organ will give the 

 required information. It can 

 be seen from the foregoing enu- 

 meration of processes, that some 

 organs have a double function 

 as regards the blood. Thus, in 

 the lung there is both renova- 

 tion by taking in oxygen, and 

 purification by getting rid of 

 carbon dioxide. The textures 

 in their internal respiration 

 take the nutriment and oxygen, 

 and give to the blood CO 2 and 

 various other waste products of 

 tissue change. 



DUCTLESS GLANDS. 



In the preceding chapters 

 the chief sources of income to 

 the blood, viz., the alimentary 



tract and the lungs, have been Vertical gectlon of the Supra _ renal 

 considered; and the changes Capsule. 1. Cortex. 2. Medulla, 

 the blood undergoes in its pas- a , Fibrous capsule; 6, External cell 

 sage through the tissues in the masses; c, Columnar layer ; d, Internal 

 systemic capillaries have cel1 masses; e, Medullary substance, 

 been alluded to. The elimina- ^ lies a large vein ' partly seen 

 tion of one of the most import- 

 ant outcomes of tissue change, namely, CO. 2 , has been described. 



It has, further, been shown that a great part of the absorbed 



